Electric-fuse case.



T. E. MURRAY. ELECTRIC FUSE CASE. APPLICATION FILED DBO. 13,1910.

991 ,008. Patented May 2 1 911.

F i v f7 l/VVE/VTOR Fuse Cases THOMAS E. MUBlB AY oF NEW YORK, N. Y.

ELECTRIC-FUSE CASE.

Specification of Letters Patent.

Patented\May 2, 1911.

i Application filed December 13, 1910. Serial No. 597,165.

To all whom it may concern:

Be it known that I, THOMAS E. MURRAY, a citizen of the United States,residing at New York, in the county of New York and State of New York,have. invented a certain new and useful Improvement inElectricspecification. I

The invention relates to electric fuses, and

consists in the-construction of the fuse case in two tubular shells, oneinclosing the other so as to form a chamber between them, into whichchamber the gas due to blowing of 1 is a perspective view of a part ofthe fuse case with one end piece in place. Fig. 2

is a longitudinal sectionthereof. Fig. 3 is,

a perspective view of a modified form of the fuse case. Fig. 4 is an endview of this modified form. Fig. 5 is a perspective view of anothermodified form of the fuse case. Fig. 6 is a cross section thereof. Fig.7 is a perspective view of still another modified form of the fuse case,and Fig. 8 is an end view of said modified form- Similar numbers ofreferenc indicate like parts.

The fuse case is ofmetal, and is made with an inner tubular shell landan outer inclosing tubular shell 2. The outer shell is provided ateachend with'a pair of preferably integral projections 3, 4- and '5, 6. Theend pieces, one of which, is shown at 7, Figs. 1 and 2, are preferablyof porcelain or other refractory lnsulating material, an are provided onone side with a recess, against the face of which the ends of the shellsabut, and with openings through which pass the projections, as 5, 6, theends of said projections being bentover as shown at 8, and received in'countersinks on the outer side of the .piece. In each end piece isacentral openingwhich receives a doubled over plate 9 of metal, betweenthe parts of which the end of the fuse strip 10 is held.-

The extremities of the plate 9 are "flanged over at 11 on the inner sideof the end piece.

The fuse case is thus secured to the end piece by the bending overofthe'projections' 3, 4 and 5, 6; the doubled over plate 9 is of whichthe following is. a

secured to the end piece,by bending over its ends'at 11, and the fusestrip is held by clamping between the parts of plate 9.

In the form of fuse. case shown in Figs. 1 and 2-, the shells 1 and 2are concentric cylinders. In Figs. 3 and 4, the case is formed of asingle sheet of metal, bent, so that the shell 1 is inclosed by shell 2.Or in other; words, in Figs. 1 and'2, an annular chamber- 12 is formedcompletely around the inner shell 1, while in Figs. 3 and 4, the chamber12 does -not entirely surround the innershell. In the form shown inFigs. 7 and 8, the case is formed of a bent sheet of metal as in Figs. 1and 2, but the outer shell is not truly cylindrical; said shell beingformed with an enlargement or corrugation at 13, so as to give increasedsize to the chamber 12. In the form shown in Figs. 5 and 6, the innershell 1 is truly cylindrical and-concentric with 'the, outer shell 2,but the outer shell is corrugated, and soldered to the inner shell atits lines of contact therewith. This produces a plurality of chambers12, 12 12 e'tc., around the inner shell. p

' In the forms shown in Figs. 1, 2, 3, 4, 7 and 8, a longitudinal lineof perforations 14 is made in the inner shell, and a similar line ofperforations 15 opposite thereto is made in the outer shell. Theperforations in the outer shell are preferably in staggered relation tothe perforations in-the inner shell. In the form shownin- Figs. 5 and 6,a line of perforations in the inner shell communi- -cates with each ofthe chambers 12, 12 12 etc., formed by the corrugations of the outershell, and in each corrugation a line of perforations 15 may be formedin staggered relation to-the inner perforations, as before.

The inner shell may contain the usual filling of refractory material,which embeds the fuse strip; and, if desired, each of the perforations,15 may be closed by a plug of plaster, which is weaker than the metalwall of the inner shell 1, so as to prevent escape of pulverized fillingmaterial, if such be used. Dhe operation is as follows: When the fuseblows, the gas suddenly generatedescapes through the perforations 14 toa sutficient extent to relieve the, shell 1 from breakin'g pressure,incidently rupturing the weak plaster plugs in said openmgs, if the samebe present. Said gas passes 1nto the chamber 9r chambers 12, and-thenceto the atmoschambers.

phere by perforations 15. In the form of case shown in Figs. 7 and 8,the outer shell is resilient, because under the sudden gas pressure ittends to take a cylindrical form, and hence the energy of the gas islargely spent against this elastic wall, which because it is elastic, isthus protected from rupture.

In the form shown in Figs. 5 and 6, the escaping gas is divided amongnumerous inner shell. It may be left loose, and in that case the gaspressure meets an elastic wall as in the form of Figs. 7, 8, because ofthe tendency of the corrugations to straighten or become obliteratedbysaid pressure.

I claim:

1. A fuse case comprising end pieces each formed integrally of a blockof refractory insulating mater1a1, and two tubular shells disposed onewithin the other and both secured at their extremities between said endpieces,

2. A fuse case comprising end pieces each formed integrally of a blockof refractory insulating materlal, and two tubular shells connectedtogether, disposed one within the other and the outer shell beingsecured at its extremities in said end pieces.

It is not essential that the outer shell in this form should be solderedto the 3. A fuse case comprising an inner tubular shell having aplurality of longitudinal lines of openings in its wall, an outerinclosing tubularshell having a corresponding plurality of longitudinalcorrugations and attached to said inner shell between the lines .ofopenings in said inner shell, and means for closingthe ends of saidshells.

4. A fuse case formed integrally of a metallic plate bent to form twotubular shells, one inclosing the other and having an air space betweenthem.

5. The combination of a fuse case, an end .piece of refractoryinsulating material thereon,'a doubled over metal plate in said endpiece, and a fuse strip entering between the parts of said plate.

6. The combination of a fuse case, an end piece of refractory insulatingmaterial, a doubled over metal plate extending through said end pieceand flanged over at each extremity on the inner side of said piece, and

a fuse strip entering between the parts of said plate.

In testimony whereof I have affixed my signature in presence of twowitnesses.

THOMASE. MURRAY. Witnesses:

GEBTRUDE T. PORTER, MAY T. MCGARRY.

